(1) Field of the Invention
The present invention relates generally to transducer arrays, and more particularly to a multi-layer composite transducer array that provides a broadband frequency response.
(2) Description of the Prior Art
A variety of sonar applications such as vehicle homing require the steering of acoustic beams. Existing homing array technology uses numerous narrowband and high-power longitutdinal tonpilz resonators to form the aperture of an active transducer. Each tonpilz resonator consists of several active and inactive mechanical components that work together as a spring-mass, single degree-of-freedom system. Unfortunately, tonpilz resonators are expensive to fabricate and offer only a limited operational bandwidth above their first length mode resonance.
To address operational bandwidth limitations of tonpilz resonators, recent work has focused on constructing multi-resonance tonpilz elements using 1–3 piezocomposites as the active component. While this approach provides improved bandwidth when compared to that of the original single-mode tonpilz resonators, these devices are still limited to first order resonance. Furthermore, the fixed-size radiation head masses inherent to tonpilz resonators prevent them from being used to realize resonators that are “frequency agile”.